Heatable pin assembly for treating thread

ABSTRACT

A heatable stretching and fixing pin assembly for thread or yarn treatment wherein a heated, stationary, cylindrical metal pin is equipped with an interchangeable thread-contacting collar which is mounted and held on the pin by a radially-compressible, annularly-fitting and heat-conducting metallic element such as a basket spring or tolerance ring.

I Umted States Patent 1191 1111 3,717,910 Fries 1 51 Feb. 27, 1973 [$41 HEATABLE PIN ASSEMBLY FOR 2,762,083 9/1956 Noguera ..29/l26 TREATING THREAD 3.425.086 2/]969 Ball 1 ..29/110.5 x

3,5l8,822 7/l970 [75] Imam: Elsenfeld Germany 2,874,410 2/1959 Kinney Assigneez Akzona Incorporated Ashevine ByBlS 6! al N.C.

Primary Examiner--Henry S. .laudon [22] Filed Apnl 1970 Attorney-Johnston, Root, OKeeffe, Keil, Thompson [21] Appl. No.: 27,224 & Shurtleff [30] Foreign Application Priority Data Apr. I9, 1969 Germany HP l9 19 935.0 [57] ABSTRACT A heatable stretching and fixing pin assembly for thread yam treatment wherein a heated, stationary [58] Fieid 117 cylindrical metal pin is equipped] with an interchange- 5' able thread-contacting collar which is mounted and held on the pin by a radially'compressible, annularly- [56] References Cited fitting and heat-conducting metallic element-such as a basket spring or tolerance ring. UNITED STATES PATENTS 1 C 3 D F aim rawmg igures 2,549,618 4/1951 McBride ..29/l26 X 2,622,182 12/1952 Forzley et al ..219/546 X Ill/Il/II/l/ 111/ 1/ I II FIG?) INVEA 1' UR:

KARL FRIES ATT'YS HEATABLE PIN ASSEMBLY FOII TREATING THREAD For the stretching or fixing of threads of thermoplastic fiber-forming polymers, heated cylindrical stretching and fixing pins are frequently arranged between the delivery and draw-off godets or between so-called feed and draw rolls. Since the threads constantly run or slide with a high speed in contact with and over a narrow section of the surface of the stationary pin, indentations and grooves are formed on the pin surface over a period of time. These groovesalter the frictional forces actingat the points of contactbetween the thread and pin. As a result, there occur very undesirable fluctuations in the thread or yarn tension. Frequently the threads stick in the grooves causing breakage.

In order to avoid these difficulties, the surface hardness of the cylindrical pins has been increased. For ex ample, surfaces composed of ceramic materials have been found to be extremely resistant to groove formation. In one known device, a ceramic collar is slipped over a heatable metal holder and is secured by means of a spreadable mounting support. The metal holder itself is secured with a screw to a conically tapered plug and has several radial slots and a bore provided with a screw thread which ends in a conically widening periphery. A threaded bolt or screw with a corresponding conical head is screwed into the bore of the metal holder after the ceramic collar has been pushed into place. By application of the conical surface of the threaded bolt against the conical periphery of the bore, the individual sections of the metal holder spread outwardly. Thereby, the ceramic collar is securely clamped in place. In this type of screw-fastening,

become more apparent upon consideration of the foluneven stresses occur in the ceramic collar and such collars then easily crack.

At the requisite high temperatures for stretching and fixing threads or yarn, e.g., far above 200C, there often occurs a sticking of the collar to the metal holder. This frequently leads, by reason of the resulting stresses, to the breakage of ceramic collars. Since even ceramic collars must be changed after a certain period of time in order to avoid groove formation, the changing of the collars is quite complicated and time-consuming. It is impractical to knock or hammer loose a ceramic collar from the metal holder while mounted directly on the stretch-twist machine because of operational difficulties and because'of damage not only to the metal holder but above all to the ceramic collar. The metal holder must therefore be disassembled from its mounting support and the collar then detached from the metal holder in the workshop. To accomplish this, it is necessary that the tightening screw first be loosened. After adjusting the metal holder and putting on and fastening a new ceramic collar, the apparatus can again be put into operation. Each change of the collar thus requires a number of steps in which there is always some danger of damage to reusable parts.

It is a primary object of the invention to provide a heated stretching and fixing pin with an interchangeable collar in combination with fastening means which will even out stresses on the collar, which will prevent the sticking of the collarto a supporting member and which will permit simple and rapid changing of individual collars. Other objects and advantages will lowing detailed specification.

It has now been found in accordance with the invention that a highly improved heatable stretching and fixing pin assembly, which can be used in combination with conventional feed and draw rolls for placing thread or'yarn in running contact with a heated surface of the assembly, is one which comprises: a heatable cylindrical metal supporting pin with means to mount said pin in a fixed position and means to heat said pin; an interchangeable collar for running contact with thread, said collar having an inner diameter fitting loosely over said pin to provide an annular space therebetween; and a heat-conducting, elastically deformable metallic element inserted in said annular space in close fitting frictional contact with said pin and said collar while being radially compressed from its normally expanded state.

The preferred structure of the pin assembly and its essential features according to the invention can best be explained in conjunction with the accompanying drawing in which:

FIG. 1 is a perspective view, partly in cross-section, of one embodiment of a stationary heated stretching and fixing pin assembly illustrating the use of a basket spring for mounting an interchangeable collar;

FIG. 2 is a vertical cross-sectional view taken along the axis of the pin assembly shown in FIG. 1; and

FIG. 3 is a similar vertical cross-sectional view, with some parts omitted, along the axis of another embodiment of the pin assembly illustrating the use of a tolerance ring for mounting an interchangeable collar.

Referring first to FIG. 1 of the drawing, a suitable framework 1 of a stretching and fixing apparatus is equipped with a pipe or conduit 2 through which a fluid heating medium is circulated. Laterally on the pipe 2 there are welded truncated steel cones 3 at intervals which correspond to the intervals between individual stretching and fixing pins. These truncated cones 3 contain a threaded bore 5 in their face surface 4 which projects from the casing 1. The cylindrical holder or supporting pin 6 for the ceramic collar 7 has at one end a conical bore which is slipped over and fitted onto the truncated cone 3. The screw 9 introduced into the bore 8 of the supporting pin 6 is screwed into the threaded bore 5 and establishes a releasably fixed connection between the pin 6 and the truncated cone 3.

The supporting pin 6 is composed of two cylindrical sections 10 and 11 having different diameters. The rear section 10 contains the above mentioned conical bore for seating on cone 3 and has a greater diameter than section 11. The front section 1 1 contains'a radially outwardly projecting flange or shoulder 12 at its exposed or free end. The collar 7 has an inner diameter sufficiently large to fit over the shoulder 12 and to form an annular space around the section 11. A basket spring 13 lies in this annular space around the section 11 and is held in position and its axial displacement prevented by the shoulder 12 and the face surface 14 of section 10. The basket spring 13 has an approximately cylindrical structure which consists of the slightly bowed spring strips 15 which are separated from one another by the slots 16 but joined at either end. One slot 17 extends over the entire axial length of the basket spring 13 to provide a split sleeve structure.

When inserting this split sleeve structure, the basket spring 13 is first radially opened or slightly bent apart along the slot 17 so that it can be pushed or thrust axially onto section 11 enclosed by the shoulder 12 and the face surface 14. Once the basket spring 13 has passed over shoulder 12, its cylindrical end portions 130 and 13b, representing an inner diameter, are relieved of tension and contract onto the outer circumference of section 11 in close-fitting frictional contact. The radially outwardly bowed longitudinal strips are then adapted to receive the ceramic collar 7 by axially sliding the collar over the pin support and basket spring assembly. The inside diameter of the ceramic collar 7 is smaller than the outside diameter of the uncompressed basket spring 13. In sliding the ceramic collar 7 over the basket spring 13, the diameter of the latter is reduced and its length is simultaneously increased. Thus, the length of the basket spring in the relaxed state is preferably slightly less than the length of section 11, i.e., between shoulder 12 and face 14 of section 10. The compressed basket spring 13 therefore has its middle portion or strips 15 lying in contact with the bore of the ceramic collar 7 while the two rims or ends 13a and 13b remain in close frictional contact with the cylindrical section 11 of the pin 6. The ceramic collar 7 is thereby fixed in its position with respect to the pin 6. Through the friction between the cylindrical section 11, the basket spring 13 and the ceramic collar 7 as well as the contact pressure forces prevailing between these parts, both circumferential and axial forces can be transmitted from the ceramic collar 7 to the pin support 6. Surprisingly, circumferential friction is sufficient to prevent rotational movement of the collar during treatment of thread in running contact around part or all of its circumference.

A housing 18 with a heat-insulating layer 19 surrounds the section 10 of pin 6 not enclosed by the ceramic collar 7, and also surrounds that part of the truncated cone 3 projecting .from the framework or face plate 1, in order to reduce the heat losses of the device. The housing 18 is pressed by the ceramic collar 7 against the face surface 14 of the pin support 6 and thereby sufficiently secured against axial displacement. Alternatively, separate mounting means can be provided to fasten housing 18 to the face plate 1. A ring member 20 secured to the housing 18 retains the heatinsulating layer 19. The framework or face plate 1 contains on its inner surface a further heat-insulating layer 21.

In FIG. 3 there is illustrated a tolerance ring 22 in place of the basket spring 13 of FIGS. 1 and 2 as a very suitable elastic or spring compressed element on the supporting pin section 11. All the other parts shown in FIG. 3 conform with those shown in FIG. 2. The tolerance ring 22 is composed of corrugated or axially oriented series of elastic rounded sections 23. It contains, like the basket spring 13, a continuous longitudinal slot (not illustrated), in order to facilitate its installation in the same manner as the basket spring. In sliding the ceramic collar 7 onto the tolerance ring 22, the corrugated elastic or spring sections 23 are compressed in radial direction. The tolerance ring is simultaneously lengthened in axial direction. The outwardly arched or bowed portions of each spring section 23 press against the ceramic collar 7 and the inwardly curved portions press against the pin 6. Through this friction contact between the individual parts and the contact pressure forces, both circumferential and radial forces can be transmitted to hold the collar 7 securely in place.

The elastically deformable and longitudinally arcuate or corrugated metallic element, in the form of a split-ring sleeve, can be readily constructed from conventional metals normally employed in making all types of springs. Steel and various steel alloys areparticularly useful, and in all cases it is desirable to achieve good heat-conducting properties.

Surprisingly, it has been found that the temperature falls only slightly between the cylindrical supporting pin 6 and the collar 7 when using the heated pin assembly of the invention so that there is no detrimental influence on the stretching and fixing treatment of running threads or yarn. This result is due to the heat transfer from the heated pin support 6 over the sleeve 13 to the collar 7. The temperature difference between the pin support and sleeve can be maintained at desirably low limits without any difficulty, especially if the effective radial thickness of the sleeve 13 is reasonably small, i.e., such that any air gap remaining between the sleeve surfaces and an oppositely disposed surface of the pin 6 or collar 7 is also small. It is especially preferred to maintain this air gap to a size of not more than 3 and preferably not more than 2 times the actual wall thickness of the metal sleeve or spring element.

The particular spring sleeve fastening element of the invention is especially suitable for mounting ceramic collars on a large number of heated and stationary supports as required in commercial operations. In like manner, however, metal collars can also be used with many of the same advantages. When the elastically deformable metallic sleeve is stressed or placed'under compression by the collar, it is radially contracted but longitudinally extended in comparison to its unstressed or relaxed state. The friction and contact pressure against both the pin 6 and collar-7 while the sleeve 13 is in the compressed state permits normal stretching and fixing treatment of running thread or yarn on the collar and also permits a very rapid and, simplified exchange of collars at any point in the operation.

Thus, the heated pin assembly of the invention essentially provides an elastic bearing or resilient sleeve support for a heated thread-contacting collar. In order to remove the collar, no screws or bolts need be loosened and there is practically no tendency for the collar to stick on the support. The collars are most simply removed from the metallic support with a pair of pliers or similar heat-insulated tool. The replacement collars can be easily inserted by hand.

The basket spring, sometimes referred to as a cage spring, is especially preferred in providing a very small air gap between the supporting pin and collar. However, excellent results have also been achieved with the sleeve or elastic fastening means identified herein as a tolerance ring which is essentially composed of corrugated or rounded spring sections axially of the sleeve. For a more detailed definition of such tolerance rings, attention is directed to W. Pampel: Kupplungen VEB Verlag Technik Berlin, 1958, page 312, FIG. 4.32i. For purposes of the present invention, it will be recognized that the arcuate slope or inclination of the corrugated sections of the tolerance ring as well as the bow or arch of the longitudinal spring sections of the basket spring must be sufficiently small to permit the collar to slide easily over the elastically deformable sleeve.

The pin assembly of the invention is normally intended for use in combination with other conventional elements of a stretching and heat-fixing apparatus employed for the continuous treatment of transported threads, yarns and the like. Thus, in addition to the pin assembly itself, one or more godets or rollers are usually employed from which the thread or yarn passes to wind partially or completely around the collar of the pin assembly. Even when operated at high transporting speeds and high temperatures as well as tight contact of the thread or yarn on the collar, the pin assembly of the invention works effectively over long periods of operation while permitting an economical and easy interchange of worn collars. The invention is hereby claimed as follows:

l. A heatable stretching and fixing pin assembly for the treatment of thread in running contact therewith which comprises:

a heatable cylindrical metal supporting pin having a radially outwardly projecting shoulder, with means to mount said pin in a fixed position and means to heat said pin;

an interchangeable collar for running contact with thread, said collar having an inner diameter fitting loosely over said pin to provide an annular space therebetween; and

a heat-conducting, elastically-deformable and radially-compressible metallic element of split sleeve structure inserted in said annular space in close fitting frictional contact with: both said pin and said collar forheat transfer therebetwcen, said metallic element being radially compressed from its normally expanded state in its assembled position where it is also axially retained on said pin by said projecting shoulder. 

1. A heatable stretching and fixing pin assembly for the treatment of thread in running contact therewith which comprises: a heatable cylindrical metal supporting pin having a radially outwardly projecting shoulder, with means to mount said pin in a fixed position and means to heat said pin; an interchangeable collar for running contact with thread, said collar having an inner diameter fitting loosely over said pin to provide an annular space therebetween; and a heat-conducting, elastically-deformable and radiallycompressible metallic element of split sleeve structure inserted in said annular space in close fitting frictional contact with both said pin and said collar for heat transfer therebetween, said metallic element being radially compressed from its normally expanded state in its assembled position where it is also axially retained on said pin by said projecting shoulder. 